In the field for the first time since 1996, Quinn shot a 2-under 68 on Thursday to join three other players in a tie for second three shots behind Martin Kaymer.
In the process, the 49-year-old Massachusetts player authored the first chapter of what could become one of the feel-good stories of this U.S. Open.
Quinn has 15-year-old son Owen carrying his clubs and his late father's memory on his mind.
"It's a dream," he said, "and I hope I don't wake up until Sunday."
For someone whose career has mostly been spent in golf's equivalent of the minor leagues, this was the round of a lifetime.
Quinn's best finish at a U.S. Open came in 1994, when he wound up 43rd at Oakmont. He missed the cut two years later at Oakland Hills and hadn't been back to one since.
"I had other opportunities to go to the qualifying, but unfortunately I had been out on the Web.com Tour a lot and I was right on the cusp of getting my card out there," Quinn said. "You couldn't really afford not to play. So unfortunately, you had to skip the Open at times."